I changed my Air-Filter after I came back from Mr.Lee warehouse. 
But I realise few different thing between my old and new air filter.
dartango, I know, K&N is the answer
, but I want to try to use the stock for the time being, coz just change other thing that day. Haha
Packaging
http://img80.imageshack.us/img80/7329/03brandnewairfilterpackagepv6.jpg
Part No for RD1 Air-Filter (shall be the same with RD2 and GK)
http://img80.imageshack.us/img80/6886/04airfilterpartnoer0.jpg
Packaging with korean word
http://img135.imageshack.us/img135/6350/09packagingvk8.jpg
Ok, after reading the packaging, work still
Took the old Air-Filter out, spotted something different
http://img80.imageshack.us/img80/9810/01justunplugiz1.jpg
Side-by-side comparison, this is not optic illusion, my old air-filter is smaller than the new 1. (Top)
http://img80.imageshack.us/img80/1835/02comparisonoldnewkj1.jpg
Bottom
http://img80.imageshack.us/img80/4391/05oldnnewbottomyr8.jpg
And then i realise few differences between the 2,
a) not Centre support bar for the old 1
http://img80.imageshack.us/img80/8483/07centersupportbarez0.jpg
b) No part no. printer on old air-filter
http://img80.imageshack.us/img80/8147/06partnoonairfilterjo1.jpg
C) no side marking
http://img135.imageshack.us/img135/3029/08sidemarkingjs4.jpg
air-filter is more or less a industry standard, so my old air-filter might be a immitation or air-filter for other car.
I haven't drive the car on street after I change the air-filter, so can't tell the different now.

But I realise few different thing between my old and new air filter.
dartango, I know, K&N is the answer

Packaging
http://img80.imageshack.us/img80/7329/03brandnewairfilterpackagepv6.jpg
Part No for RD1 Air-Filter (shall be the same with RD2 and GK)
http://img80.imageshack.us/img80/6886/04airfilterpartnoer0.jpg
Packaging with korean word
http://img135.imageshack.us/img135/6350/09packagingvk8.jpg
Ok, after reading the packaging, work still
Took the old Air-Filter out, spotted something different
http://img80.imageshack.us/img80/9810/01justunplugiz1.jpg
Side-by-side comparison, this is not optic illusion, my old air-filter is smaller than the new 1. (Top)
http://img80.imageshack.us/img80/1835/02comparisonoldnewkj1.jpg
Bottom
http://img80.imageshack.us/img80/4391/05oldnnewbottomyr8.jpg
And then i realise few differences between the 2,
a) not Centre support bar for the old 1
http://img80.imageshack.us/img80/8483/07centersupportbarez0.jpg
b) No part no. printer on old air-filter
http://img80.imageshack.us/img80/8147/06partnoonairfilterjo1.jpg
C) no side marking
http://img135.imageshack.us/img135/3029/08sidemarkingjs4.jpg
air-filter is more or less a industry standard, so my old air-filter might be a immitation or air-filter for other car.
I haven't drive the car on street after I change the air-filter, so can't tell the different now.